1. Field
This disclosure relates to passive electronic devices, and more particularly to passive electronic devices that are subjected to applied voltages. Even more particularly, it is related to voltage subtraction and timing circuits used with sneak current cancellation in dual-sense, single-read memory devices.
2. Background
Passive electronic devices generally do not generate signals based upon their own internal circuits. Typically, passive devices must be addressed or requested to provide some sort of signal. One example of a passive device is a memory. Generally, memories do not provide the data stored in them until some other device, such as a processor, requests the data. Similarly, the memory receives data to store, rather than generating data to store.
Some types of passive devices, including memories, have elements being held at a potential, even though those elements may not be undergoing active addressing. Returning to the memory example, a memory cell may be held at a particular potential in order to allow the cell to retain the data stored there. This potential is typically less than that required to address a cell for either reading or writing.
However, application of the voltage may cause the cell to ‘leak’ charge over a period of time, resulting in a low level of current. While the current created by any one element does not cause problems, when multiplied by the number of elements in the device, the current could become one. The cumulative charge over time becomes a significant current, referred to here as ‘sneak’ current, and results in a high level of noise in the signal.
It would be desirable for a method and apparatus that could cancel the sneak current, reducing the noise in the system utilizing the passive electronic devices.